/*
 * Copyright (c) 1982, 1986, 1988, 1990, 1993
 *	The Regents of the University of California.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 *	@(#)udp_usrreq.c	8.4 (Berkeley) 1/21/94
 * udp_usrreq.c,v 1.4 1994/10/02 17:48:45 phk Exp
 */

/*
 * Changes and additions relating to SLiRP
 * Copyright (c) 1995 Danny Gasparovski.
 *
 * Please read the file COPYRIGHT for the
 * terms and conditions of the copyright.
 */

#include <stdlib.h>
#include "slirp/slirp.h"
#include "slirp/ip_icmp.h"

struct udpstat udpstat;

struct SLIRPsocket udb;

/*
 * UDP protocol implementation.
 * Per RFC 768, August, 1980.
 */
#ifndef COMPAT_42
int udpcksum = 1;
#else
int udpcksum = 0; /* XXX */
#endif

struct SLIRPsocket *udp_last_so = &udb;

void udp_init() { udb.so_next = udb.so_prev = &udb; }
/* m->m_data  points at ip packet header
 * m->m_len   length ip packet
 * ip->ip_len length data (IPDU)
 */
void udp_input(m, iphlen) struct SLIRPmbuf *m;
int iphlen;
{
        struct ip *ip;
        struct udphdr *uh;
        /*	struct SLIRPmbuf *opts = 0;*/
        int len;
        struct ip save_ip;
        struct SLIRPsocket *so;

        DEBUG_CALL("udp_input");
        DEBUG_ARG("m = %lx", (long)m);
        DEBUG_ARG("iphlen = %d", iphlen);

        udpstat.udps_ipackets++;

        /*
         * Strip IP options, if any; should skip this,
         * make available to user, and use on returned packets,
         * but we don't yet have a way to check the checksum
         * with options still present.
         */
        if (iphlen > sizeof(struct ip)) {
                ip_stripoptions(m, (struct SLIRPmbuf *)0);
                iphlen = sizeof(struct ip);
        }

        /*
         * Get IP and UDP header together in first SLIRPmbuf.
         */
        ip = mtod(m, struct ip *);
        uh = (struct udphdr *)((SLIRPcaddr_t)ip + iphlen);

        /*
         * Make SLIRPmbuf data length reflect UDP length.
         * If not enough data to reflect UDP length, drop.
         */
        len = ntohs((u_int16_t)uh->uh_ulen);

        if (ip->ip_len != len) {
                if (len > ip->ip_len) {
                        udpstat.udps_badlen++;
                        goto bad;
                }
                m_adj(m, len - ip->ip_len);
                ip->ip_len = len;
        }

        /*
         * Save a copy of the IP header in case we want restore it
         * for sending an ICMP error message in response.
         */
        save_ip = *ip;
        save_ip.ip_len += iphlen; /* tcp_input subtracts this */

        /*
         * Checksum extended UDP header and data.
         */
        if (udpcksum && uh->uh_sum) {
                memset(&((struct ipovly *)ip)->ih_mbuf, 0, sizeof(struct mbuf_ptr));
                ((struct ipovly *)ip)->ih_x1 = 0;
                ((struct ipovly *)ip)->ih_len = uh->uh_ulen;
                /* keep uh_sum for ICMP reply
                 * uh->uh_sum = cksum(m, len + sizeof (struct ip));
                 * if (uh->uh_sum) {
                 */
                if (cksum(m, len + sizeof(struct ip))) {
                        udpstat.udps_badsum++;
                        goto bad;
                }
        }

        /*
         *  handle DHCP/BOOTP
         */
        if (ntohs(uh->uh_dport) == BOOTP_SERVER) {
                bootp_input(m);
                goto bad;
        }

        /*
         *  handle TFTP
         */
        if (ntohs(uh->uh_dport) == TFTP_SERVER) {
                tftp_input(m);
                goto bad;
        }

        /*
         * Locate pcb for datagram.
         */
        so = udp_last_so;
        if (so->so_lport != uh->uh_sport || so->so_laddr.s_addr != ip->ip_src.s_addr) {
                struct SLIRPsocket *tmp;

                for (tmp = udb.so_next; tmp != &udb; tmp = tmp->so_next) {
                        if (tmp->so_lport == uh->uh_sport && tmp->so_laddr.s_addr == ip->ip_src.s_addr) {
                                tmp->so_faddr.s_addr = ip->ip_dst.s_addr;
                                tmp->so_fport = uh->uh_dport;
                                so = tmp;
                                break;
                        }
                }
                if (tmp == &udb) {
                        so = NULL;
                } else {
                        udpstat.udpps_pcbcachemiss++;
                        udp_last_so = so;
                }
        }

        if (so == NULL) {
                /*
                 * If there's no socket for this packet,
                 * create one
                 */
                if ((so = socreate()) == NULL)
                        goto bad;
                if (udp_attach(so) == -1) {
                        DEBUG_MISC((dfd, " udp_attach errno = %d-%s\n", errno, strerror(errno)));
                        sofree(so);
                        goto bad;
                }

                /*
                 * Setup fields
                 */
                /* udp_last_so = so; */
                so->so_laddr = ip->ip_src;
                so->so_lport = uh->uh_sport;

                if ((so->so_iptos = udp_tos(so)) == 0)
                        so->so_iptos = ip->ip_tos;

                /*
                 * XXXXX Here, check if it's in udpexec_list,
                 * and if it is, do the fork_exec() etc.
                 */
        }

        so->so_faddr = ip->ip_dst;   /* XXX */
        so->so_fport = uh->uh_dport; /* XXX */

        iphlen += sizeof(struct udphdr);
        m->m_len -= iphlen;
        m->m_data += iphlen;

        /*
         * Now we sendto() the packet.
         */
        if (so->so_emu)
                udp_emu(so, m);

        if (sosendto(so, m) == -1) {
                m->m_len += iphlen;
                m->m_data -= iphlen;
                *ip = save_ip;
                DEBUG_MISC((dfd, "udp tx errno = %d-%s\n", errno, strerror(errno)));
                icmp_error(m, ICMP_UNREACH, ICMP_UNREACH_NET, 0, strerror(errno));
        }

        m_free(so->so_m); /* used for ICMP if error on sorecvfrom */

        /* restore the orig SLIRPmbuf packet */
        m->m_len += iphlen;
        m->m_data -= iphlen;
        *ip = save_ip;
        so->so_m = m; /* ICMP backup */

        return;
bad:
        m_freem(m);
        /* if (opts) m_freem(opts); */
        return;
}

int udp_output2(struct SLIRPsocket *so, struct SLIRPmbuf *m, struct sockaddr_in *saddr, struct sockaddr_in *daddr, int iptos) {
        struct udpiphdr *ui;
        int error = 0;

        DEBUG_CALL("udp_output");
        DEBUG_ARG("so = %lx", (long)so);
        DEBUG_ARG("m = %lx", (long)m);
        DEBUG_ARG("saddr = %lx", (long)saddr->sin_addr.s_addr);
        DEBUG_ARG("daddr = %lx", (long)daddr->sin_addr.s_addr);

        /*
         * Adjust for header
         */
        m->m_data -= sizeof(struct udpiphdr);
        m->m_len += sizeof(struct udpiphdr);

        /*
         * Fill in SLIRPmbuf with extended UDP header
         * and addresses and length put into network format.
         */
        ui = mtod(m, struct udpiphdr *);
        memset(&ui->ui_i.ih_mbuf, 0, sizeof(struct mbuf_ptr));
        ui->ui_x1 = 0;
        ui->ui_pr = IPPROTO_UDP;
        ui->ui_len = htons(m->m_len - sizeof(struct ip)); /* + sizeof (struct udphdr)); */
        /* XXXXX Check for from-one-location sockets, or from-any-location sockets */
        ui->ui_src = saddr->sin_addr;
        ui->ui_dst = daddr->sin_addr;
        ui->ui_sport = saddr->sin_port;
        ui->ui_dport = daddr->sin_port;
        ui->ui_ulen = ui->ui_len;

        /*
         * Stuff checksum and output datagram.
         */
        ui->ui_sum = 0;
        if (udpcksum) {
                if ((ui->ui_sum = cksum(m, /* sizeof (struct udpiphdr) + */ m->m_len)) == 0)
                        ui->ui_sum = 0xffff;
        }
        ((struct ip *)ui)->ip_len = m->m_len;

        ((struct ip *)ui)->ip_ttl = ip_defttl;
        ((struct ip *)ui)->ip_tos = iptos;

        udpstat.udps_opackets++;

        error = ip_output(so, m);

        return (error);
}

int udp_output(struct SLIRPsocket *so, struct SLIRPmbuf *m, struct sockaddr_in *addr) {
        struct sockaddr_in saddr, daddr;

        saddr = *addr;
        if ((so->so_faddr.s_addr & htonl(0xffffff00)) == special_addr.s_addr) {
                saddr.sin_addr.s_addr = so->so_faddr.s_addr;
                if ((so->so_faddr.s_addr & htonl(0x000000ff)) == htonl(0xff))
                        saddr.sin_addr.s_addr = alias_addr.s_addr;
        }
        daddr.sin_addr = so->so_laddr;
        daddr.sin_port = so->so_lport;

        return udp_output2(so, m, &saddr, &daddr, so->so_iptos);
}

int udp_attach(so) struct SLIRPsocket *so;
{
        struct sockaddr_in addr;

        if ((so->s = socket(AF_INET, SOCK_DGRAM, 0)) != -1) {
                /*
                 * Here, we bind() the socket.  Although not really needed
                 * (sendto() on an unbound socket will bind it), it's done
                 * here so that emulation of ytalk etc. don't have to do it
                 */
                memset(&addr, 0, sizeof(struct sockaddr_in));
                addr.sin_family = AF_INET;
                addr.sin_port = 0;
                addr.sin_addr.s_addr = INADDR_ANY;
                if (bind(so->s, (struct sockaddr *)&addr, sizeof(addr)) < 0) {
                        int lasterrno = errno;
                        closesocket(so->s);
                        so->s = -1;
#ifdef _WIN32
                        WSASetLastError(lasterrno);
#else
                        errno = lasterrno;
#endif
                } else {
                        /* success, insert in queue */
                        so->so_expire = curtime + SO_EXPIRE;
                        insque(so, &udb);
                }
        }
        return (so->s);
}

void udp_detach(so) struct SLIRPsocket *so;
{
        closesocket(so->s);
        /* if (so->so_m) m_free(so->so_m);    done by sofree */

        sofree(so);
}

struct tos_t udptos[] = {{0, 53, IPTOS_LOWDELAY, 0},             /* DNS */
                         {517, 517, IPTOS_LOWDELAY, EMU_TALK},   /* talk */
                         {518, 518, IPTOS_LOWDELAY, EMU_NTALK},  /* ntalk */
                         {0, 7648, IPTOS_LOWDELAY, EMU_CUSEEME}, /* Cu-Seeme */
                         {0, 0, 0, 0}};

u_int8_t udp_tos(so) struct SLIRPsocket *so;
{
        int i = 0;

        while (udptos[i].tos) {
                if ((udptos[i].fport && ntohs(so->so_fport) == udptos[i].fport) ||
                    (udptos[i].lport && ntohs(so->so_lport) == udptos[i].lport)) {
                        so->so_emu = udptos[i].emu;
                        return udptos[i].tos;
                }
                i++;
        }

        return 0;
}

#ifdef EMULATE_TALK
#include "talkd.h"
#endif

/*
 * Here, talk/ytalk/ntalk requests must be emulated
 */
void udp_emu(so, m) struct SLIRPsocket *so;
struct SLIRPmbuf *m;
{
        struct sockaddr_in addr;
        socklen_t addrlen = sizeof(addr);
#ifdef EMULATE_TALK
        CTL_MSG_OLD *omsg;
        CTL_MSG *nmsg;
        char buff[sizeof(CTL_MSG)];
        u_char type;

        struct talk_request {
                struct talk_request *next;
                struct SLIRPsocket *udp_so;
                struct SLIRPsocket *tcp_so;
        } * req;

        static struct talk_request *req_tbl = 0;

#endif

        struct cu_header {
                uint16_t d_family;  // destination family
                uint16_t d_port;    // destination port
                uint32_t d_addr;    // destination address
                uint16_t s_family;  // source family
                uint16_t s_port;    // source port
                uint32_t so_addr;   // source address
                uint32_t seqn;      // sequence number
                uint16_t message;   // message
                uint16_t data_type; // data type
                uint16_t pkt_len;   // packet length
        } * cu_head;

        switch (so->so_emu) {

#ifdef EMULATE_TALK
        case EMU_TALK:
        case EMU_NTALK:
                /*
                 * Talk emulation. We always change the ctl_addr to get
                 * some answers from the daemon. When an ANNOUNCE comes,
                 * we send LEAVE_INVITE to the local daemons. Also when a
                 * DELETE comes, we send copies to the local daemons.
                 */
                if (getsockname(so->s, (struct sockaddr *)&addr, &addrlen) < 0)
                        return;

#define IS_OLD (so->so_emu == EMU_TALK)

#define COPY_MSG(dest, src)                                                                                                      \
        {                                                                                                                        \
                dest->type = src->type;                                                                                          \
                dest->id_num = src->id_num;                                                                                      \
                dest->pid = src->pid;                                                                                            \
                dest->addr = src->addr;                                                                                          \
                dest->ctl_addr = src->ctl_addr;                                                                                  \
                memcpy(&dest->l_name, &src->l_name, NAME_SIZE_OLD);                                                              \
                memcpy(&dest->r_name, &src->r_name, NAME_SIZE_OLD);                                                              \
                memcpy(&dest->r_tty, &src->r_tty, TTY_SIZE);                                                                     \
        }

#define OTOSIN(ptr, field) ((struct sockaddr_in *)&ptr->field)
                /* old_sockaddr to sockaddr_in */

                if (IS_OLD) { /* old talk */
                        omsg = mtod(m, CTL_MSG_OLD *);
                        nmsg = (CTL_MSG *)buff;
                        type = omsg->type;
                        OTOSIN(omsg, ctl_addr)->sin_port = addr.sin_port;
                        OTOSIN(omsg, ctl_addr)->sin_addr = our_addr;
                        strncpy(omsg->l_name, getlogin(), NAME_SIZE_OLD);
                } else { /* new talk */
                        omsg = (CTL_MSG_OLD *)buff;
                        nmsg = mtod(m, CTL_MSG *);
                        type = nmsg->type;
                        OTOSIN(nmsg, ctl_addr)->sin_port = addr.sin_port;
                        OTOSIN(nmsg, ctl_addr)->sin_addr = our_addr;
                        strncpy(nmsg->l_name, getlogin(), NAME_SIZE_OLD);
                }

                if (type == LOOK_UP)
                        return; /* for LOOK_UP this is enough */

                if (IS_OLD) { /* make a copy of the message */
                        COPY_MSG(nmsg, omsg);
                        nmsg->vers = 1;
                        nmsg->answer = 0;
                } else
                        COPY_MSG(omsg, nmsg);

                /*
                 * If if is an ANNOUNCE message, we go through the
                 * request table to see if a tcp port has already
                 * been redirected for this socket. If not, we solisten()
                 * a new socket and add this entry to the table.
                 * The port number of the tcp socket and our IP
                 * are put to the addr field of the message structures.
                 * Then a LEAVE_INVITE is sent to both local daemon
                 * ports, 517 and 518. This is why we have two copies
                 * of the message, one in old talk and one in new talk
                 * format.
                 */

                if (type == ANNOUNCE) {
                        int s;
                        u_short temp_port;

                        for (req = req_tbl; req; req = req->next)
                                if (so == req->udp_so)
                                        break; /* found it */

                        if (!req) { /* no entry for so, create new */
                                req = (struct talk_request *)malloc(sizeof(struct talk_request));
                                req->udp_so = so;
                                req->tcp_so = solisten(0, OTOSIN(omsg, addr)->sin_addr.s_addr, OTOSIN(omsg, addr)->sin_port,
                                                       SS_FACCEPTONCE);
                                req->next = req_tbl;
                                req_tbl = req;
                        }

                        /* replace port number in addr field */
                        addrlen = sizeof(addr);
                        getsockname(req->tcp_so->s, (struct sockaddr *)&addr, &addrlen);
                        OTOSIN(omsg, addr)->sin_port = addr.sin_port;
                        OTOSIN(omsg, addr)->sin_addr = our_addr;
                        OTOSIN(nmsg, addr)->sin_port = addr.sin_port;
                        OTOSIN(nmsg, addr)->sin_addr = our_addr;

                        /* send LEAVE_INVITEs */
                        temp_port = OTOSIN(omsg, ctl_addr)->sin_port;
                        OTOSIN(omsg, ctl_addr)->sin_port = 0;
                        OTOSIN(nmsg, ctl_addr)->sin_port = 0;
                        omsg->type = nmsg->type = LEAVE_INVITE;

                        s = socket(AF_INET, SOCK_DGRAM, IPPROTO_IP);
                        addr.sin_addr = our_addr;
                        addr.sin_family = AF_INET;
                        addr.sin_port = htons(517);
                        sendto(s, (char *)omsg, sizeof(*omsg), 0, (struct sockaddr *)&addr, sizeof(addr));
                        addr.sin_port = htons(518);
                        sendto(s, (char *)nmsg, sizeof(*nmsg), 0, (struct sockaddr *)&addr, sizeof(addr));
                        closesocket(s);

                        omsg->type = nmsg->type = ANNOUNCE;
                        OTOSIN(omsg, ctl_addr)->sin_port = temp_port;
                        OTOSIN(nmsg, ctl_addr)->sin_port = temp_port;
                }

                /*
                 * If it is a DELETE message, we send a copy to the
                 * local daemons. Then we delete the entry corresponding
                 * to our socket from the request table.
                 */

                if (type == DELETE) {
                        struct talk_request *temp_req, *req_next;
                        int s;
                        u_short temp_port;

                        temp_port = OTOSIN(omsg, ctl_addr)->sin_port;
                        OTOSIN(omsg, ctl_addr)->sin_port = 0;
                        OTOSIN(nmsg, ctl_addr)->sin_port = 0;

                        s = socket(AF_INET, SOCK_DGRAM, IPPROTO_IP);
                        addr.sin_addr = our_addr;
                        addr.sin_family = AF_INET;
                        addr.sin_port = htons(517);
                        sendto(s, (char *)omsg, sizeof(*omsg), 0, (struct sockaddr *)&addr, sizeof(addr));
                        addr.sin_port = htons(518);
                        sendto(s, (char *)nmsg, sizeof(*nmsg), 0, (struct sockaddr *)&addr, sizeof(addr));
                        closesocket(s);

                        OTOSIN(omsg, ctl_addr)->sin_port = temp_port;
                        OTOSIN(nmsg, ctl_addr)->sin_port = temp_port;

                        /* delete table entry */
                        if (so == req_tbl->udp_so) {
                                temp_req = req_tbl;
                                req_tbl = req_tbl->next;
                                free(temp_req);
                        } else {
                                temp_req = req_tbl;
                                for (req = req_tbl->next; req; req = req_next) {
                                        req_next = req->next;
                                        if (so == req->udp_so) {
                                                temp_req->next = req_next;
                                                free(req);
                                                break;
                                        } else {
                                                temp_req = req;
                                        }
                                }
                        }
                }

                return;
#endif

        case EMU_CUSEEME:

                /*
                 * Cu-SeeMe emulation.
                 * Hopefully the packet is more that 16 bytes long. We don't
                 * do any other tests, just replace the address and port
                 * fields.
                 */
                if (m->m_len >= sizeof(*cu_head)) {
                        if (getsockname(so->s, (struct sockaddr *)&addr, &addrlen) < 0)
                                return;
                        cu_head = mtod(m, struct cu_header *);
                        cu_head->s_port = addr.sin_port;
                        cu_head->so_addr = our_addr.s_addr;
                }

                return;
        }
}

struct SLIRPsocket *udp_listen(port, laddr, lport, flags) u_int port;
u_int32_t laddr;
u_int lport;
int flags;
{
        struct sockaddr_in addr;
        struct SLIRPsocket *so;
        socklen_t addrlen = sizeof(struct sockaddr_in);
        int opt = 1;

        if ((so = socreate()) == NULL) {
                free(so);
                return NULL;
        }
        so->s = socket(AF_INET, SOCK_DGRAM, 0);
        so->so_expire = curtime + SO_EXPIRE;
        insque(so, &udb);

        memset(&addr, 0, sizeof(struct sockaddr_in));
        addr.sin_family = AF_INET;
        addr.sin_addr.s_addr = INADDR_ANY;
        addr.sin_port = port;

        if (bind(so->s, (struct sockaddr *)&addr, addrlen) < 0) {
                udp_detach(so);
                return NULL;
        }
        setsockopt(so->s, SOL_SOCKET, SO_REUSEADDR, (char *)&opt, sizeof(int));
        /*	setsockopt(so->s,SOL_SOCKET,SO_OOBINLINE,(char *)&opt,sizeof(int)); */

        getsockname(so->s, (struct sockaddr *)&addr, &addrlen);
        so->so_fport = addr.sin_port;
        if (addr.sin_addr.s_addr == 0 || addr.sin_addr.s_addr == loopback_addr.s_addr)
                so->so_faddr = alias_addr;
        else
                so->so_faddr = addr.sin_addr;

        so->so_lport = lport;
        so->so_laddr.s_addr = laddr;
        if (flags != SS_FACCEPTONCE)
                so->so_expire = 0;

        so->so_state = SS_ISFCONNECTED;

        return so;
}
